biostudies-literatureBoleslavska BCzech Academy of SciencesChildren with Cancer UKSwiss National Science FoundationThe Ministry of Education, Youth and SportsCharles University Grant AgencyCzech Science FoundationCHILDREN with CANCER UK12274-12290https://www.ebi.ac.uk/biostudies/studies/S-EPMC9757067biostudies-literatureUnknown50(21)R-loops are three-stranded nucleic acid structures composed of an RNA:DNA hybrid and displaced DNA strand. These structures can halt DNA replication when formed co-transcriptionally in the opposite orientation to replication fork progression. A recent study has shown that replication forks stalled by co-transcriptional R-loops can be restarted by a mechanism involving fork cleavage by MUS81 endonuclease, followed by ELL-dependent reactivation of transcription, and fork religation by the DNA ligase IV (LIG4)/XRCC4 complex. However, how R-loops are eliminated to allow the sequential restart of transcription and replication in this pathway remains elusive. Here, we identified the human DDX17 helicase as a factor that associates with R-loops and counteracts R-loop-mediated replication stress to preserve genome stability. We show that DDX17 unwinds R-loops in vitro and promotes MUS81-dependent restart of R-loop-stalled forks in human cells in a manner dependent on its helicase activity. Loss of DDX17 helicase induces accumulation of R-loops and the formation of R-loop-dependent anaphase bridges and micronuclei. These findings establish DDX17 as a component of the MUS81-LIG4-ELL pathway for resolution of R-loop-mediated transcription-replication conflicts, which may be involved in R-loop unwinding.Nucleic acids researchDDX17 helicase promotes resolution of R-loop-mediated transcription-replication conflicts in human cells.PMC9757067310030_184716LTAUSA19096184716L2005220011332217PGTaSFA\10002730811931003021-22593X22-08294S20-333Kanagaraj RJanscak PAndrs MIbini ONBoleslavska BOravetzova AHasanova ZShukla KNascakova ZDobrovolna JfalseDDX17 helicase promotes resolution of R-loop-mediated transcription-replication conflicts in human cells.R-loops are three-stranded nucleic acid structures composed of an RNA:DNA hybrid and displaced DNA strand. These structures can halt DNA replication when formed co-transcriptionally in the opposite orientation to replication fork progression. A recent study has shown that replication forks stalled by co-transcriptional R-loops can be restarted by a mechanism involving fork cleavage by MUS81 endonuclease, followed by ELL-dependent reactivation of transcription, and fork religation by the DNA ligase IV (LIG4)/XRCC4 complex. However, how R-loops are eliminated to allow the sequential restart of transcription and replication in this pathway remains elusive. Here, we identified the human DDX17 helicase as a factor that associates with R-loops and counteracts R-loop-mediated replication stress to preserve genome stability. We show that DDX17 unwinds R-loops in vitro and promotes MUS81-dependent restart of R-loop-stalled forks in human cells in a manner dependent on its helicase activity. Loss of DDX17 helicase induces accumulation of R-loops and the formation of R-loop-dependent anaphase bridges and micronuclei. These findings establish DDX17 as a component of the MUS81-LIG4-ELL pathway for resolution of R-loop-mediated transcription-replication conflicts, which may be involved in R-loop unwinding.2022-01-01T00:00:00Z2022 Nov2026-04-08T18:10:06.2Z2025-04-19T10:47:10.934ZS-EPMC97570673645399410.1093/nar/gkac1116